Предполагается, что вы объединили ячейки:
Sub Tester()
Dim c As Range, rngMerge As Range
For Each c In ActiveSheet.Range("A1").Resize(1, 100).Cells
Set rngMerge = c.MergeArea
If rngMerge.Cells.Count > 1 Then
c.UnMerge
rngMerge.Value = rngMerge.Cells(1).Value
End If
c.Value = JoinUp(c.Resize(3, 1), "_")
Next c
ActiveSheet.Range("A2:A3").EntireRow.Delete
End Sub
Function JoinUp(rng As Range, Optional Delim As String = "") As String
Dim c As Range, rv As String
For Each c In rng.Cells
If Len(c.Value) > 0 Then
rv = rv & IIf(Len(rv) > 0, Delim, "") & c.Value
End If
Next c
JoinUp = rv
End Function